Self-Sustaining On-Site Production of Electricity and/or Steam for Use in the In Situ Processing of Oil Shale and/or Oil Sands

ABSTRACT

Oil shale and/or oil sands are utilized to generate electricity and/or steam at the site of the oil shale/sands deposit in an in situ process for recovering oil from the deposit. Bulk shale/sands material is removed from the deposit and combusted to generate thermal energy. The thermal energy is utilized to heat water to generate steam. The steam can be used directly in the in situ process or utilized to drive a steam turbine power generator located in close proximity to the deposit to generate electricity. The electricity generated on-site may be utilized to drive an in situ conversion process that recovers oil from the oil shale/sands deposit. Also, the exit steam generated by the on-site turbine generator can be used on-site to drive the in-situ conversion process.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/819,601, filed on Jul. 10, 2006, by William B. Hendershot and titled “Self-Sustaining On-Site Production of Electricity for Use in the In Situ processing of Oil Shale and/or Oil Sands.” U.S. Provisional Application No. 60/819,601, filed Jul. 10, 2006, is hereby incorporated by reference herein in its entirety.

This patent application is a Continuation-In-Part of co-pending application Ser. No. 11/429,907, filed on May 8, 2006, by William B. Hendershot, titled “Self-Sustaining On-Site Production of Electricity Utilizing Oil Shale and/or Oil Sands Deposits’, which is a Continuation-In-Part of application Ser. No. 11/093,690, filed on Mar. 30, 2005, by William B. Hendershot, titled “Self-Sustaining On-Site Production of Electricity Utilizing Oil Shale”, which (1) is a Continuation-In-Part of application Ser. No. 10/618,948, filed on Jul. 14, 2003, by William B. Hendershot, titled “On-site Production of Electricity Utilizing Oil Shale”, now abandoned, and (2) claims the benefit of Provisional Patent Application No. 60/560,498, filed on Apr. 7, 2004, by William B. Hendershot, titled “On-site Production of Electricity Utilizing Oil Shale.” application Ser. No. 11/429,907, application Ser. No. 11/093,690, application Ser. No. 10/618,948, and Provisional Patent Application No. 60/560,498 are each hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to energy production from oil shale and/or oil sands deposits and, in particular, to an efficient technique for producing electricity and/or steam in close proximity to the site of an oil shale/sands deposit and utilizing a portion of the on-site-generated electricity and/or the on-site produced steam, or both, to facilitate the in situ retorting of oil shale/sands. The use and recycling of resources and heat energy developed at the site of the oil shale/sands deposit further contributes to the self-sustaining aspect of the invention.

2. Discussion of the Related Art

As discussed in a 2005 report authored by Bartis et al. for the RAND Corporation and titled “Oil Shale Development in the United States”, it is well known that there are very large oil shale deposits in a number of locations throughout the world. These oil shale deposits hold some of the largest oil reserves in the world. The reason that only a very small amount of this oil is currently extracted from these deposits for use in producing energy is the prohibitively high cost, in terms of both economics and environmental impact, associated with extracting the oil from the oil shale. The RAND Corporation report provides a detailed discussion of the prospects and policy issues related to oil shale development in the United States. Similar issues apply to the vast oil sands deposits that exist in North America, primarily in Canada.

A number of methods for recovering oil from oil shale have been proposed. The technology disclosed in U.S. Pat. No. 4,265,307, issued on May 5, 1981, and titled “Shale Oil Recovery”, is an example.

As discussed in '307 patent, oil shale is composed of inorganic matter (rock) and organic matter called “kerogen.” When oil shale is heated at elevated temperatures on the order of 600° F. to 900° F. in the absence of significant oxygen, kerogen is destructively distilled to form a hydrocarbon gas, shale oil and carbon. Shale oil at elevated temperature is in the vapor phase, while the carbon is in the form of coke. Continued heating of shale oil causes decomposition to form more gas and more coke.

As further discussed in the '307 patent, beginning in the 1920's, the first proposals for recovering oil from shale were referred to as “true in situ combustion.” As the name suggests, these methods involved the in situ, or in the ground, combustion of the oil shale. Heat necessary for recovering the hydrocarbons was to be supplied by in situ combustion, combustion being accomplished along a combustion front that moved from one end of the oil shale deposit to the other end of the deposit during the recovery operation.

The true in situ combustion technique was first tried in the 1950's and was attempted a number of times in the 1950's and the 1960's. In carrying out this process, small fissures were introduced into the oil shale deposit by hydrofrac techniques prior to combustion in order to expedite the passage of vaporous shale oil out of the bed. Unfortunately, the true in situ combustion technique was not successful.

In the early 1970's, a modification of the true in situ combustion technique was first tried. This technique, referred to as the “modified in situ combustion technique”, differs from the true in situ combustion technique in that, prior to in situ combustion, partial mining around the oil shale deposit is accomplished to provide a greater flow path for the escape of the shale oil. Also prior to combustion, the shale oil deposit is broken up or fragmentized (referred as “rubblized’) into chunks or pieces. This is usually accomplished by means of explosives. However, the modified in situ combustion technique also proved to be ineffective in larger shale oil deposits, where yields were only around 30% of theoretical.

U.S. Pat. No. 4,472,935, issued to Acheson et al. on Sep. 25, 1984, discloses an example of a modified in situ oil shale combustion technique. In accordance with the method disclosed in the '935 patent, a subsurface oil shale formation is penetrated by both a production well and an injection well. While the shale itself remains in the ground, the fluids produced by the production well are delivered through a line into an above ground separator in which low heating value (LHV) gases in the produced fluids are separated from the liquids in the produced fluids. The liquids are discharged from the bottom of the separator into a line for off-site delivery and the LHV gases are discharged from the top of the separator into a feed line. The LHV gases are preheated, mixed with air and then burned in a catalytic combustion chamber. The combustion products discharged from the combustion chamber are then expanded in a turbine to generate electricity.

In addition to in situ combustion, other techniques have been proposed for the recovery of shale oil from oil shale by the in situ heating of the oil shale. These techniques include the utilization of electrical energy for heating the oil shale and the utilization of radio frequency energy rather than combustion to furnish the necessary heat.

Oil sands deposits are typically exploited using either the modified in situ combustion technique described above or an open pit mining process.

The modified in situ combustion technique involves the process described in the above-cited Acheson et al. '935 patent, wherein both a production well and an injection well are formed in the oil sands deposit. The injection well is used to drive heat into the deposit, forcing the “bitumen” hydrocarbons in the deposit into the production well for extraction.

In the more commonly used open pit mining technique, the bitumen-containing oil sands are removed from the deposit using scooping and conveyor systems. The extracted bulk oil sands are then transported to a processing facility using either huge dump trucks or a water-slurry transport system. The processing plant uses water to separate the bitumen form the sand. The bitumen is then processed to remove impurities and then further processed in a coking tower system that ultimately provides a “sweet crude” hydrocarbon product. The open pit mining technique is clearly environmentally insensitive and energy inefficient.

The above-cited RAND report describes an in situ retorting process envisaged in the early 1980s by researchers at Shell Oil, which they named the In-Situ Conversion Process. Referring to FIG. 1, according to the In-Situ Conversion Process, a volume of shale is heated by electric heaters that are placed in vertical holes drilled through the entire thickness (more than a thousand feet) of a section of oil shale. To obtain even heating over a reasonable period of time, fifteen to twenty-five heating holes are drilled per acre. After heating for two to three years, the targeted volume of the deposit reaches a temperature of between 650 and 700° F. This very slow heating to a relatively low temperature, compared with the plus-900° F. temperature common in the above-described surface retorting processes, is sufficient to cause the chemical and physical changes required to release the oil from the shale.

FIG. 2 shows the major process steps associated with Shell in situ conversion process. As part of the site preparation, the Shell process uses ground-freezing technology to establish an underground barrier around the perimeter of the extraction zone, creating a “freeze wall” by circulating a refrigerated fluid through a series of wells drilled around the extraction zone. In addition to preventing groundwater from entering the extraction zone, the freeze wall keeps hydrocarbons and other products generated by retorting from leaving the project perimeter during ground heating, product extraction and post extraction ground cooling. Of course, both the site preparation and the extraction phases involve the construction of power plants and power transmission lines to supply the electricity both to the refrigeration systems and to the underground heaters.

While, as indicated above, numerous attempts have been made to effectively capture oil from oil shale and/or oil sands deposits over the years, no technique has yet been developed that provides a commercially-viable and environmentally-sensitive production level technique for recovering energy from these huge deposits.

SUMMARY OF THE INVENTION

The present invention provides systems and methods for generating electricity and/or steam in close proximity to oil shale and/or oil sands deposits and, preferably, with optimum utilization of local supplemental energy resources and recycled energy and materials. The electricity and/or steam generated on-site is then utilized to drive an in situ conversion process of the type described above.

In accordance with the general concepts of the invention, an electrical power generating facility is located in close proximity to an oil shale deposit or an oil sands deposit (hereinafter referred to inclusively as an “oil shale/sands deposit”). Oil shale/sands removed from the deposit is provided to an on-site, above ground burn container in bulk form. Supplemental heat energy, preferably obtained from on-site fuel resources and/or recycled materials, may be provided to supplement the combustion process in the on-site burn container. The heat energy generated by the combustion process in the burn container is utilized to heat water to generate steam. The steam drives a steam turbine power generator that is part of the on-site power generating facility. The steam turbine generates electricity at least a portion of which is utilized at the site to drive an in situ recovery process, for example, a process similar to the Shell in situ conversion process described above, that recovers oil from the oil shale/sands deposit. Alternatively, the steam may be used directly in the in situ conversion process.

Calculations made utilizing widely available data show that, if one acre of an oil shale/sands deposit contains 1,500,000 barrels of oil (as in the case of the Green River Formation discussed in the above-cited RAND report), a recovery technique in accordance with the present invention, that is, generating electricity and /or steam on site using oil shale/sands from the deposit and then utilizing the on site generated electricity and/or steam to drive an in situ conversion process, would produce approximately a net 547,000 barrels of oil per acre. At a price of $50 per barrel, the value of oil product produced from a single acre of the deposit would be $27,350,000, or $17.5 billion per square mile. It is reliably estimated that the Green River Formation and its main basins cover about 16,000 square miles in Utah, Wyoming and Colorado.

In an embodiment of the present invention, the oil shale/sands removed from the deposit to feed the above ground burn container is taken from the perimeter of the targeted in situ process recovery zone, thereby defining a trench around the in situ recovery zone. Creation of a perimeter trench around the in situ recovery zone not only provides the energy resource needed to drive the on-site generation of electricity for use in the in situ recovery process, but also, in the case of the Shell in situ conversion process, minimizes the “freeze wall” energy requirement.

These and additional features and advantages of the present invention will be more fully appreciated upon consideration of the following detailed description of the invention and the accompanying drawings that set forth a number of illustrative embodiments in which the concepts of the invention are utilized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a known in situ conversion process for recovering oil from an oil shale deposit.

FIG. 2 is flow chart showing the general steps involved in the FIG. 1 in situ conversion process.

FIG. 3 is a flow chart illustrating a method of recovering oil from oil shale/sands in accordance with the concepts of the present invention.

FIG. 4 is a block diagram illustrating an embodiment of a system and method for generating electricity from oil shale/sands deposits in accordance with the concepts of the present invention.

FIG. 5 is a block diagram illustrating a more detailed embodiment of a system and method for generating electricity from oil shale/sands deposits in accordance with the concepts of the present invention.

FIG. 6 is a schematic drawing illustrating a dual parabolic solar reflector utilizable in generating electricity from oil shale/sands deposits in accordance with the concepts of the present invention.

FIG. 7 is a schematic drawing illustrating an alternate embodiment of a dual parabolic solar reflector utilizable in generating electricity from oil shale/sands deposits in accordance with the concepts of the present invention.

FIG. 8 is a block diagram illustrating an alternate embodiment of a system and method for generating electricity and/or hydrocarbon products from oil shale/sands deposits in accordance with the concepts of the present invention.

FIGS. 9A-9D illustrate utilization of spent hot oil shale/oil sands to preheat bulk oil shale/oil sands input to a recovery vessel in accordance with the concepts of the present invention.

FIGS. 10A and 10B show the utilization of a sealing wall in a trench formed around a targeted in situ oil recovery zone, in accordance with the concepts of the present invention.

FIGS. 11A and 11B show two embodiments of a piping scheme for utilizing steam generated on the site of an oil shale/sands deposit in the in situ recovery of oil from the deposit

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a technique that utilizes oil shale and/or oil sands to generate electricity and/or steam in close proximity to the site of the oil shale/sands deposit for use in the in situ recovery of oil from the oil shale/sands deposit, thereby making the oil recovery process self-sustaining.

FIG. 3 shows the steps of a self-sustaining method of recovering oil from an oil shale/sands deposit. An electrical generating system 10 generates electricity 12 on site utilizing hydrocarbon products recovered from the oil shale/sands deposit 14. The electricity 12 generated on site is utilized to recover oil from the deposit utilizing an in situ recovery technique; for example, as shown in FIG. 3, the electricity generated on site can be used to drive both the refrigeration function 16 and the underground heating function 18 of the Shell in situ conversion process.

FIG. 4 shows one embodiment of a system 100 for generating electricity on-site utilizing oil shale and/or oil sands in accordance with the present invention.

The system 100 includes an electrical power generating facility 102 that is located in close proximity to an oil shale/sands deposit 104. It is desirable to locate the electrical generating facility 102 as close to the deposit 104 as possible, the location of the facility 102 being dependant upon local conditions, including the size of the deposit 104 itself. The distance from the deposit 104 to the generating facility should, preferably, be less than 20 miles.

The power generating facility 102 includes a steam turbine power generator 106 of the conventional type utilizable for generating electricity. As indicated in FIG. 4, in accordance with this embodiment of the invention, oil shale and/or oil sands 108 in bulk form (i.e., greater than about 1.5 in. diameter in the case of oil shale) is removed from the deposit 104 and provided to an on-site, above ground conventional burn container 110, such as, for example, a fluidized bed reactor. Those skilled in the art will appreciate that, in the case of oil shale, the bulk oil shale 108 can be “rubblized” or “pulverized” (i.e., crushed to pieces less than about 1.5 in. diameter) prior to its introduction into the above ground burn container 110. Supplemental fuel 112, which can be, for example, propane, but which preferably is fuel obtained from a renewable source local to the deposit 104 (e.g., ethanol obtained from corn grown in proximity to the deposit 104) may be provided to the burn container 110 such that hydrocarbons contained in the bulk oil shale/sands 108 are combusted in the burn container 110 to generate thermal energy. The thermal energy generated by the burn container 110 is utilized to heat water 114, preferably provided by a local source, to generate steam 116. The steam 116 drives the steam turbine power generator 106 to generate electricity 118. At least a portion of the on site generated electricity 118 can be utilized to drive a conventional in situ recovery process, as discussed above. Any excess electricity 118 not required for the in situ process can be distributed as desired utilizing a conventional electricity distribution system or grid or, as discussed in greater detail below, used on-site to make the power generation process more self-sustaining.

FIG. 5 shows a more detailed embodiment of the FIG. 4 system 100. As shown in FIG. 5, recoverable by-products 121 resulting from the combustion of bulk oil shale/sands 108 in the above ground burn container 110 include fine potash, including potassium carbonate and potassium hydroxide. It is well known that potassium carbonate is used as a granular powder in making glass, enamel and soaps; potassium hydroxide is a caustic white solid used as bleach and in making soap, common dyes and alkaline batteries (lye). Thus, the commercial need for potassium carbonate and potassium hydroxide could justify the cost of disposing of this by-product of the burn container 110. Furthermore, the spent rock and/or sands 122 resulting from the combustion of the oil shale/sands 108 in the burn container 110 can be returned to the original deposit 104 to minimize the environmental impact of “mining” the bulk oil shale/sands 108.

As in the FIG. 4 system, thermal energy generated in the burn container 110 heats water 114, preferably from a local source, to produce steam 116 that drives a steam turbine generator 106. Steam turbine generator 106 generates electricity 118 that is utilized in an in situ recovery process, exported for off-site use, or used in the electricity generation process.

As further shown in FIG. 5, exhaust steam heat 124 from the steam turbine power generator 106, which can be at a temperature of 350-400° C., and/or exhaust heat 126 from the burn container 110, can be recycled and used to provide preheat energy 128 to the bulk oil shale/sands 108 as it comes from the deposit 104 to the burn container 110. The combination of the recycled preheat energy 128 and the supplemental fuel 112 can result in a temperature that will cause the bulk oil shale/sands 108 entering the burn container 110 to be easily crumpled to a fine powder, thereby facilitating removal of the shale oil and other hydrocarbons contained in the bulk material 108 as it is heated in the burn container 110. As mentioned above, if the heat provided from these supplemental and/or recycled sources is insufficient, some amount of refining, e.g., rubblizing/pulverizing of bulk oil shale, may be required prior to introduction of the bulk material 108 into the burn container 110 to facilitate more efficient recovery of thermal energy from the shale oil hydrocarbons contained in the bulk material 108. Crushing can be powered utilizing the excess steam 124 and/or the electricity 118 generated on-site.

Alternatively, some form of radiant energy, e.g. microwaves, could be used to preheat the bulk material 108, thereby dissolving the kerogen contained therein. As in the FIG. 4 embodiment, the supplemental fuel 112 provided to the burn container 110 can be propane or other locally obtained waste material such as for example, wood, sawdust, trash or manure that can be utilized to generate heat in the burn container 110 or to preheat the bulk material 108.

As further shown in FIG. 5, the water 114 utilized to generate steam 116 for driving the steam turbine power generator 106 can be preheated utilizing a parabolic solar reflector system 130 (described in greater detail below).

The steam exhaust heat 124 from the steam turbine power generator 106, which, as stated above, typically will be around 350-400° C., can also be utilized to assist in the fermentation of locally grown corn to produce ethanol as a supplemental fuel 112 for the burn container 110. Alternatively, the ethanol could be used in dissolving kerogen contained in the bulk material 108, thereby improving the efficiency of the combustion process in the burn container 110.

FIG. 6 shows an embodiment of a parabolic solar reflector system 130 that can be used in the FIG. 5 system. The center of the parabolic reflector system 130 near the axis, which is flatter and more perpendicular to the sun's rays, is used to generate electrical energy utilizing solar panels 131 mounted on the parabolic reflector surface 133. The outer edge reflects solar rays to a black sphere 135 located at a focal point to heat the water ultimately provided as the steam source to the turbine generator 106.

As stated above, exhaust steam 124 from the steam turbine power generator 106 can be used to preheat the bulk material 108 or can be reused as input to the steam tank.

FIG. 7 provides a more detailed illustration of a preferred embodiment of a parabolic solar reflector system 130. In the FIG. 7 embodiment, the parabolic reflector 130 includes a first parabolic reflecting surface 132 having a first curvature that conforms, as illustrated, to the equation Y²=20x. The parabolic reflector 130 also includes a second parabolic reflecting surface 134 that conforms to a second equation, shown in FIG. 3 as Y²=10x. Both the first parabolic reflecting surface 132 and the second parabolic reflecting surface 134 have the same focal point. A black sphere 136 located at the common focal point of the first parabolic reflecting surface 132 and the second parabolic reflecting surface 134 receives water 114 from the input source and provides preheated water to the burn container 110 for generation of steam 116. As further shown in FIG. 7, the first parabolic reflecting surface 132 of the parabolic reflector 130 has solar collectors 138 mounted thereon for generating electricity from the solar energy captured by the solar collectors. The system 130 can include solar tracking equipment that continuously adjusts the position of the reflecting surfaces 132, 134 in response to changes in the position of the sun to obtain maximum capture of solar energy.

FIG. 8 illustrates an alternate embodiment of a system 500 for the self-sustaining generation of electricity using oil shale and/or oil sands removed from an oil shale/sands deposit 502. As in the above-described embodiments of the invention, oil shale and/or oil sands in bulk form 504 are removed from the deposit 502 and provided to an on-site, above ground burn container 506, such as, for example, a fluidized bed reactor. As discussed above, supplemental fuel 508 may be provided to the burn container 506 such that hydrocarbons contained in the bulk material 504 are combusted to generate thermal energy within the burn container 506. Thermal energy generated in the burn container 506 is utilized to heat water 510, preferably from a local source 511, to generate steam 512. The steam 512 drives a steam turbine power generator 514 that generates electricity 516 for off-site distribution 518; as discussed below, a portion of the electricity generated on-site can be used in the energy recovery process.

As further shown in FIG. 8, bulk material 504 a may also be removed from the deposit 502 and provided to a preheat system 520. Preheated bulk material 522 from the preheat system 520 is provided to a surface recovery vessel 524 in which heat is used to drive hydrocarbons from the preheated bulk oil shale/sands material 522 in liquid form 525 and/or in vapor form 526, as is done in conventional surface oil shale retorting processes; in contrast to the conventional surface retorting technique, the heat required for the surface recovery vessel 524, preferably, all derives from the deposit 502. The hydrocarbon vapors 524 driven from the bulk material 522 are cooled in a condenser 528 to provide liquid oil and/or hydrocarbon product 530 that can be distributed off-site together with the liquid product 525; a portion of the product 525, 530 can used as supplemental fuel in various other stages of the recovery process. Condenser 528 may be cooled using water, which, in this case, would require additional use of water from the local source 511. However, as shown on FIG. 8, preferably, the condenser 528 is electrically driven by power 518 generated by the on-site generator 514, thereby reducing the burden on the local water resource 511.

Also, although not shown in the FIG. 8 block diagram, a portion (preferably less than 20%) of the oil/hydrocarbon output 525, 530 of the surface recovery vessel 524 can be recycled to assist combustion in any or all of the burn container 506, the preheat system 533 and the surface recovery vessel 524 itself. The combustion efficiency in each of these systems can be optimized by varying the percentage of the various fuels used in the system. Also, if one or more of these systems is not functioning properly at any given time, the generation of electricity and oil/hydrocarbon product can continue by simply increasing the utilization of the other systems. For example, the burn container 506 can act as a buffer to supply larger amount of electricity while the surface recovery vessel 524 is being loaded/unloaded between cycles.

As further shown in FIG. 8, a portion of the electrical 516 energy generated by the steam turbine power generator 514 can be utilized to heat the surface recovery vessel 524. Furthermore, supplemental heat for the recovery vessel 524 can be obtained by the combustion of bulk oil shale/sands material 504 b taken from the deposit 502.

As additionally shown in FIG. 8, spent bulk material 532 that results from the heating process in the surface recovery vessel 524, and that can have a temperature in the range of 450° C., can be provided to a preheat system 534 in which the water 510 is preheated prior to introduction to the burn container 506, thereby reducing the fuel burden on the burn container 506 and increasing the overall efficiency of the system 500.

FIGS. 9A-9D combine to show an embodiment of a preheating system 520 (FIG. 8) that can be utilized to preheat the bulk material 504 a that is provided to the surface recovery vessel 524. As shown in the side view of FIG. 9A and its corresponding cross section in FIG. 9B, the preheat system 520 includes a lower conveyer belt 536 that runs in a direction (shown by the lower arrow) that carries spent material from the recovery vessel 524 and a second, upper conveyer belt 538 that runs in an opposite direction to deliver bulk material 504 a from the deposit 502 to the recovery vessel 524. The dual-conveyer belt system 536, 538 is surrounded by insulation 540 on all four sides, as illustrated in FIGS. 9A and 9B, in order to minimize heat loss and, thus, obtain maximum benefit of the recycled heat provided by the spent material 532 from the recovery vessel 524. Thus, oil sand/shale material 502 a to be input to the recovery vessel 524 can be preheated by spent hot shale/sand material 532 that is removed from the recovery vessel 524 and passes on the lower conveyer 536 in an opposite direction. The volume of the spent shale/sands material 532 and preheated oil shale/sands 522 on the conveyor belts can equal a full load in the recovery vessel 524; however, up to 25% of the spent shale/sands 532 at 450° C. could remain in the recovery vessel 524 for use in preheating the next cycle of bulk material introduced to the vessel 524. FIGS. 9C and 9D provide details of the transfer of spent shale/sand 532 and pre-heated oil shale/sand 522 to and from the recovery vessel 524, respectively.

It should be understood that, although FIG. 8 shows the utilization of only one steam turbine generator 514 in the system 500, multiple steam generators could be utilized with, for example, some of the generators providing power for use in an in situ recovery process and some of the generators providing power to an off site grid. Using a number of smaller generators (e.g., one steam generator per four square miles of the overall oil shale/sands deposit 502) would, thus, provide greater flexibility to the system 500. The use of small portable steam generators would enable these generators to be moved from site to site on the deposit 502 as the different areas of the deposit 502 are developed, thereby reducing the overall cost of energy production.

As discussed above, the Shell in situ conversion process requires the creation of a “freeze zone” around the perimeter of the targeted deposit recovery zone. Creation of the “freeze zone” requires a large amount of electricity to drive the refrigeration system needed to sustain the freeze zone for up to three years. In accordance with an embodiment of the present invention, shown in FIG. 10A, the energy requirement for such a “freeze zone” can be significantly reduced, if not eliminated, by removing the oil shale/sands needed for the on-site generation of electricity, as discussed in detail above, from the perimeter of the in situ recovery zone, thereby creating a trench 600 around the in situ recovery zone 602. A combination of a trench 10 and a reduced-size refrigeration system utilizing holes 604 drilled in the bottom of the trench 600, as shown in FIG. 10B, could also be utilized.

It might be possible for heated liquid oil to seep through the wall 606 of the trench 600. Therefore, as shown in FIGS. 10A and 10B, reusable metal plates 608 that fit together to form an oil seal could be used so that oil from the in situ recovery zone 602 does not pass into the trench 600. As further shown in FIGS. 10A and 10B, a catch trough 610 can be placed between the inside of the plates 608 and the oil shale/sands deposit 602 to capture “seepage” oil, which can be recovered for use off-site, or on site as discussed above.

Also, suitable thermal insulation 612 can be applied on the outside of the metal plates 608 to greatly reduce heat loss from the in situ recovery zone 602. The insulated perimeter must have a lower outward heat flow from the heated in situ zone than having the same heated zone surrounded by the conventional “freeze zone” utilized in the Shell process.

The oil shale/sands that remains in the zone between the fully liquefied in situ recovery zone and the sealing plates around the perimeter of the recovery zone can be used after the oil is recovered form the in situ zone to generate electricity on site as discussed above.

Several potential uses of the exhaust steam heat from the steam turbine power generator 106 are discussed above in conjunction with the FIG. 5 block diagram. As stated above, this exhaust steam 124 is typically at a temperature of 350-400° C. (assuming a 1000° C. steam input temperature). This exhaust steam 124 could be also be used to heat the in situ recovery zone in the above-described in situ conversion process. It is believed that the amount of exhaust steam available from the steam turbine power generator would be sufficient to provide 100% of the thermal energy required to heat the in situ zone in accordance with the typical operating parameters for this process; alternatively, a portion of the exhaust steam could be utilized to supplement the electricity used to drive the heating of the in situ zone, thereby reducing the overall electrical power requirement for this purpose. Water resulting from the utilization of the exhaust steam for this purpose could be recovered from the in situ zone and recycled for use in steam generation as discussed above.

The steam exiting the steam turbine generator can be held at 400° C. or higher by controlling the input temperature of the steam to the turbine generator. As shown in FIG. 11A, the exit steam can then be circulated through the oil shale/sand deposit in pipes to cause the oil in the deposit to liquefy. In this embodiment of the invention, the steam does not mix with the oil. Rather, the steam remains inside the pipes, which preferably are inserted in the drilled holes in the in situ hot zone, as discussed above. These same holes may be used to insert electrical heating rods, as discussed above, to supplement the steam heating if needed.

Since the heat energy in the exit steam from the turbine generator contains about 50% of the input energy, as compared to 36% in the on-site generated electrical energy, using the exit steam is more efficient than using on-site generated electricity to heat the oil shale/sands in the in situ hot zone.

The further cooled steam, after utilization for heating the oil shale/sands in the in situ conversion process, can be recycled for use in the boiler.

Example: Compare oil/dollars out of one square mile of an oil shale/sands deposit using on-site generated steam versus on-site generated electricity in the in situ conversion process in accordance with the invention as described above.

Electricity

At 36% efficiency, it takes 446,400 MegW per square mile, or 1,240,00 MW heat into the boiler to drive the in situ process using on-site generated electricity.

Steam

At 50% efficiency, it takes 892,800 MegW heat into the boiler to drive the in situ process using exit steam from the on-site turbine generator.

That is, the steam alternative is 28% more efficient than the electricity alternative and the generator still produces 446,400 MegW electricity that can be used on or off site. This 446,400 MegW of electricity is equivalent to 274,000,000 barrels of oil from the deposit. Thus, in the recycled steam embodiment of the invention, the overall output of 1 square mile of the oil shale/sands deposit is the equivalent of 1,234,000,000 barrels of oil which, at $50 per barrel, has a value of about $62 Billion.

Those skilled in the art will appreciate that the utilization of the exhaust steam is a very efficient utilization of a by-product of the on-site generation of electricity and, because it is generated on-site, can be utilized at substantially full efficiency because it does not need to be piped any great distance for use. However, of the exit steam from the turbine generator is used more than about 5 miles from the turbine generator, the heat from the stem will dissipate greatly, thereby reducing oil recovery efficiency.

As an alternative, use of the steam from the burn container 110 (see FIGS. 4 and 5, for example) directly for heating the hot zone in an in situ recovery process within a 5 mile radius of the burn container 110 (i.e. the surrounding 80 square miles) with the steam turbine generator 106 turned off, the output steam from the burn container 110 would not need to be over 1000° C. as in the case when the turbine generator 106 is being powered by the steam from the burn container 110. Using the steam directly from the burn container 110 would greatly reduce the amount of burned oil shale/sands used to heat the burn container 110 by about 36%. When the turbine generator 106 is needed to provide electricity to heat the hot zone area out to about 300 square miles around the turbine generator 106, the generator 106 is simply turned on and the output temperature of the steam from the burn container 110 is increased to 1000° C. Those skilled in the art will appreciate that it is not difficult to run electricity up to about 10 miles. Also, any combination of on-site generated electricity and on-site generated steam can be used in the in-situ recovery process.

The recovery process described above would require about 50 steam turbine generator systems to recover oil from the Colorado/Utah/Wyoming oil shale deposits described in the above-cited RAND report. After using one of these systems to fully exploit one region of the deposit, the system could be moved and reused at one or more additional sites.

Steam may also be used to pressure the liquid oil generated in the in-situ recovery process toward the exit port. This steam would not cool substantially because it would be in contact with hot oil and shale. Additional drill holes might be needed at the outer perimeter of the in situ hot zone for the insertion of steam in these perimeter regions.

It should also be understood that systems of the type described above could include the latest available pollution control technology. For example, all of the hydrocarbon combustion systems could be fitted with scrubbers to minimize air pollution.

All steps of the processes needed for the on-site generation of electricity from oil shale can be facilitated by the electric power generated from on-site. For example, the following can be achieved by using this electricity:

-   raw mining of oil shale and/or oil ands -   removal of raw oil shale/oil sands from the mine -   crushing oil shale -   heating crushed oil shale and/or oil sands to the point of     evaporation -   condensing oil vapor to reclaim the liquid oil -   pumping the liquid oil to a desired location for cracking

It should be understood that various alternatives to the embodiments of the invention described herein might be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and systems within the scope of these claims and their equivalents be covered thereby. 

1. A self-sustaining method of recovering oil shale/sands deposit, the method comprising: generating electricity at the site of the oil shale/sands deposit utilizing hydrocarbon products recovered from the oil shale/sands deposit; and utilizing the electricity generated at the site of the oil shale/sands deposit to drive an in situ conversion process for recovering oil from the oil shale/sands deposit.
 2. (canceled)
 3. A method as in claim 1, and wherein the electricity generated at the site of the oil shale/sands deposit is utilized to drive the underground heating function of the in situ conversion process.
 4. A method as in claim 1, and wherein the step of generating electricity at the site of the oil shale/sands deposit comprises: locating an electrical power generating facility that includes a steam turbine power generator in close proximity to the oil shale/sands deposit; removing oil shale/sands from the oil shale/sands deposit in bulk form; providing the removed oil shale/sands to an above ground burn container; providing supplemental fuel to the burn container such that hydrocarbons contained in the oil shale/sands provided to the burn container are combusted to generate thermal energy; using the thermal energy generated by the burn container to heat water to generate steam; providing the steam to the steam turbine power generator such that the steam turbine power generator generates electricity on the site of the oil shale/sands deposit.
 5. A method as in claim 4, and wherein the oil shale/sands are removed from a perimeter portion of the oil shale/sands deposit to define a perimeter trench around an interior portion of the oil shale/sands deposit.
 6. (canceled)
 7. A method as in claim 4, and wherein the oil shale/sands provided to the above ground burn container comprises rubblized oil shale.
 8. A method as in claim 4, and wherein the oil shale/sands provided to the above ground burn container comprises pulverized oil shale.
 9. A method as in claim 4, and further comprising: recovering potash generated by combustion of the oil shale/sands hydrocarbons.
 10. A method as in claim 4, and further comprising: returning spent oil shale/sands resulting from combustion of the oil shale/sands hydrocarbons to the oil shale/sands deposit.
 11. A method as in claim 4, and further comprising: preheating the water prior to utilizing the thermal energy generated by the burn container to heat the water to generate steam.
 12. A method as in claim 11, and further comprising: preheating the water utilizing a parabolic solar reflector.
 13. A method as in claim 12, and further comprising: adjusting the position of the parabolic reflector to track the position of the sun.
 14. A method as in claim 11, and further comprising: preheating the water utilizing a dual parabolic reflector that includes a first parabolic surface having a focal point and a second parabolic reflecting surface having the same focal point as the first parabolic reflecting surface, the water being passed through the common focal point of the first and second parabolic reflecting surfaces.
 15. A method as in claim 14, and wherein the first parabolic reflecting surface has solar collectors mounted thereon for generating electricity from solar energy captured by the solar collectors.
 16. A method as in claim 4, and wherein the supplemental fuel includes propane.
 17. A method as in claim 4, and wherein the supplemental fuel is obtained from a source located in close proximity to the oil shale/sands deposit.
 18. A method as in claim 17, and wherein the supplemental fuel comprises ethanol derived from a crop grown in close proximity to the oil shale/sands deposit.
 19. A method as in claim 4, and further comprising: utilizing exhaust heat from the electrical power generating facility to heat the oil shale/sands provided to the burn container.
 20. A method as in claim 4, and further comprising: utilizing exhaust heat from the electrical power generating facility to pre-heat the oil shale/sands prior to its introduction to the burn container.
 21. A method as in claim 4, and further comprising: providing supplemental fuel to pre-heat the oil shale/sands prior to its introduction to the burn container.
 22. A method as in claim 1, and wherein the step of generating electricity at the site of the oil shale/sands deposit comprises: removing oil shale/sands from the oil shale/sands deposit in bulk form; combusting the removed bulk oil shale/sands above ground to generate heat energy; utilizing the heat energy at the site of the oil shale/sands deposit to generate electricity; utilizing at least some of the generated electricity in the removing and/or combusting steps. 23.-37. (canceled)
 38. A system that generates electricity and hydrocarbon products, the system comprising: an electrical power generating system that includes an on-site steam turbine power generator located in close proximity to an oil shale/sands deposit: an above ground burn container that combusts oil shale/sands material removed from the oil shale/sands deposit to produce thermal energy utilized to produce steam that drives the steam turbine power generator to generate electricity; and an on-site in situ conversion system that recovers hydrocarbon products from the oil shale/sands deposit utilizing electricity generated by the steam turbine power generator. 39.-42. (canceled)
 43. A method of recovering oil from an oil shale/sands deposit, the method comprising: removing oil shale/sands material from a perimeter region of a portion of the oil shale/sands deposit to define a perimeter trench around said portion of the oil shale/sands deposit; utilizing the oil shale/sands material removed from the oil shale/sands deposit to generate electricity at the site of the oil shale/sands deposit; and utilizing the electricity generated at the site of the oil shale/sands deposit in the in situ recovery of oil from said portion of the oil shale/sands deposit. 44.-48. (canceled) 